Machine-switching telephone-exchange system.



'c. L. GOODRUM. MACHINE SWITCHINGTELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-11,1916.

Patented Apr. 3, 1917.

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l i Application one September 11, me seriaiuu 119,511.

To al'lwiwm 2 2? may comer-u y Be it kuownthut 1, CHARLES L. GoonnUM .u citizen of the United States,residiug at Brooklyn, in the county of liii c and State of New York, have im'euted. cei lain new and useful Improvements in MachineSwitching Telephone-limbunge @ystems, of which the following is a full. clean-concise, and (description. illllis invention relates to telephone e2;- change ystems involving private branch e2ichange Working.

In the circuit arrangement of this invention some of the subscribers in the private branch exchange may he-culled by any other suhscriherin the sys em by means 'ol" automntic switches. 'Others oi. the private brunch exchange subscribers. however. in receive calls through the iu ervention of an. operator at the private h ".ch. exchange; that to say, when u conne r is sci; upon any of suchv lines, instead of the station thereof being automatically signaled, the private exchange operator signaled and, by means of her listening hey, bridges her talking set across the calling line, and in quires the Wants of the 1 Grilling party. Means is provided whereby she'may thcn either allow the line upon which the connector has been set' by the outside party toloe signaled, or release the connector, interim ing the calling party that the call cannot be completed. I

' The circuit arrangement of this invention is particularly useful in such systems wherei in automatic Working is desired for the 1najority of the private hr 1h exchange subscriber's, and it is not desirable that certain of such subscribers be directly accessible to outside parties for mine reasons, among which may he mentioned the 'Waste of time incident to people culling ollicers in the co1upally served by the private branch exchung 7 and asking questions which could he more rcailily token cure of hyemployees, In the circuit arrangement of this invention such calls are diverted by the opcratorto the proper channels. v

Referring to the accompanying drawing, which illustrates onl so much of a telephone exchange system as is necessary for o. comprehension of the invention, the invention will be best understood by describing. by rel? ercnce to such drawing, the detailed opera.- tion of the system.

Specification of Letters; Intent.-

understood that although serum; nil-Quorum true? it substation "which. only the t, t are shown, 'setin motion. in oony welhkn'own inenner, to hunt for the line. then the finder conuects vith such, lincfthe first selector FS, the brushes. 2; 3 and 4 21.51 tcrininuls 5, 6 and 7 only cfwhich are shown, set by the sender S at the call ing substation in the ell-known manner upon it trunk tormiimting in a connector G at the private branch exchange. It will be only one selector is shown, the connection would in practice he built up over melanin of switches, 9' l e culling line has been. thus ex n: l" e steppingrelay 1 r "l ovecthe calling line circuit, uiul by at acting its ing its right the circuit of release magnet Rd, and at its front Contact connects the, hack contact of stepping relay 8 to the primary magnet PM of the conuecton.

The calling party now operates his sender 51' to transmit thetens digit of the Wanted luiunherl The sender, in restoring inteirrupts the line circuit a number of times corresponding to the tens digit of the "Wanted number. Upon retraction of the step ping relay zmnature 8., an impulse is sent over the following circuit to primary magnet PM to positioniuset of brushes 10 11 152 and 13 in opeutive relation terminals eontaiuii r those of the Wanted lino: .l'rcc pole of ttery, magnet PM, side switch arm 14- and. its first contact, armature 50 and each contact oi busy'reley cond uctors 15 and 46, right armature and front contact of relay 9, armature and lurch; contact of relay 8 to grounds A slow relaylii, in nwallel with magnet Phi energizes upon the first impulse and, being slow-acting, remains energized during the transmission ofthe impulses. When the sender '5 restores and maintains the line circuit closed, relayB remains After an interval the slow relay 16 beconies doncrgized, opening the circuit ol' the connector side switch escape magnet 17, closed when this roluy was enernixed. The es ape magnet 11, in denergiz inn". releases the side switch into position 2, In this position the secondy mugneti lli l is substituted fortlie primary magnet PM;

to the group of armature, interposes a break in The calling party now operates his sender S to transmit the units digit of the wanted number. The secondary magnet SM, in response to these impulses, steps the positioned set of brushes 10, 11, 12 and 13 over the terminals of the selected group. The slow relay-16 is againenergized in parallel with the secondary magnet SM, and again ener gizes the escape magnet 17. When the sender S restores and maintains the line circuit closed, the slow relay 16, after an interval, :denergizes, opening the circuit of escape magnet 17, which passes the side switch to position 3.

Assuming that the terminal 43 of the line upon which the connector has been set is a'non-restirictedline and is idle, ,the following circuit i's""clo'sed for the escape magnet 17 to close the ringing circuit: escape magnet '17, arm 22 and its third contact, armature and back contact of ringing cut-off relay RCO, conductors 23, 24 to ground at the left armature, and front contact of relay 9. Magnet 17, in attracting its armature, closes the ringing circuit as follows: ground, ringing generator 25, battery, relay RCO, left armature and back contact of relay 21, armature and front contact of magnet 17, arm 26 on its thirdcontact, brush 12, terminal 27, through the bell 28 and condenser 29 at the substation B, terminal 30, brush'll, arm 31, and its third contact to ground.

When the arty at substation B removes his receiver, t e relay RCO energizes, opening the circuit of escape magnet 17, which thereupon deenergizes and passes the side switch to position 4. In moving out of position 3 the ringingcircuit is opened, and in position 4 talking current is fed to the called arty over the followingcircuit: free pole of? battery, retardation coil winding 33, conductor 34, arm 31 and its fourth contact, brush 11, terminal 30, throu%h the telephonic apparatus at substation terminal 27, brush 12, arm 26 and its fourth contact, conductor 35, retardation coil windin 36 to ground. Talking current is fed to t e calling party over the windings of relay 8. The calling and called ends of the talking circuit are conductively separated and inductively united by condensers 37 and 38.

Assuming now that the connector was set onterminals 41, 42, 43, 40 of a restricted idle line, whose terminal 41 is grounded, the lamp 19 becomes lighted over the follow.- ing circuit:.grounded' terminal 41, bush 10, key OK," lamp 19, right-hand armature and back contact of relay BR, arm 20, and its second contact, relay 21, free pole of battery. The brush 10 engages the terminal 41 before the slow relay 16 has time to deenergize and o n the circuit of escape magnet 17. The side switch is thus held in position 2 until after relay 21 has had time to energize.

circuit ,before the escape magnet has had time to attract its armature and close the same in position 3. The operator, noticing the lighted lam 19, actuates her listening key LK, which bridges her talking set (not shown) across the calling line. After talking witlrtlle calling subscriber, she may by depressing the key OK, permit the line upon which the connector rests to be signaled, or, by pressing the release key RK, release the connector. In the former case the depression of the key OK unlocks relay 21, and extinguishes the lamp 19. The relay 21, in ret-racting its left armature, connects the ringing generator 25 to the called line, from which point on the operations are the same as already traced.

On the other hand, assuming the connection is not to be extended, the operator so informs the calling party and depresses the release key RK, which results in the energization of the release magnet Rel over the following circuit: free pole of battery, magnet'ReZ, primary off-normal contact PON, conductors139 and 40' :ey RK, to ground. When the connector reaches its normal position the off-normal contact PON opens and unlocks the release magnet.

Assume now that the line upon which the connector is set is busy. The test terminal 40, insuch event, is ounded over the side switch arm 41 and t e third contact of the connector connected with such line or a side switch arm at the finder, depending on whether the line is a called or calling line. Going back to that point in the operation where the calling part transmits the units digit of the called num er, it will be remembered that the slow relay 16 is energized in parallel with the secondary magnet SM, and that this relay at its armature and front contact completes a circuit for the escapement magnet 17, the side switch being at this time in position 2. When the connector brushes 10, 11, 12 and 13 reach the selected set of terminals 41, 42, 43 and 40, and before the relay 16 has had time to retract its armature, the following circuit is closed in position 2 o f the side switch over grounded terminal 40, of the busy line, brush 13, arm 41 and its second contact, right winding of relay BR, and free pole of battery. Relay BR in attracting its inner armature locks itself up over side switch arm 45 and its secondcontact. At armature 51 it closes a circuit Ytomaintain the escape magnet 17 energized to hold the side switch in osition 2, at armature 50 it interposes a brea in the circuit of magnet SM to prevent the calling subscriber from transmitting any more 1mpulses, and at its outer left aw ture connects a source of busy tone current 42' to the conductor 35 and thence to the calling line to inform the calling party that the desired line is busy.

-When such party replaces his receiver the connector release magnet Rd is energized over the following circuit: free pole of battery, magnet Rel, contact PON, armature and back contacts of relays 9 and 8, to ground. Magnet Rel restores the connector and when the brush shaft thereof reaches its normal position, it opens contact :PON and unlocks the release magnet. This magnet in operating restores the side switch in the well-known manner. The right armature of a relay BB is provided in order to prevent unnecessarily signaling the operator in the event the selected line is a restricted line and busy.

What is claimed is:

1. he a telephone exchange system, the combination with restricted and non-restricted telephonelines, an automatic switchwherein said lines terminate, a sender adapted to set said switch on said lines, asource of signaling current, an operators position, a telephone set and supervisory signal thereat, means for automatically connecting said source to non-restricted lines when the switch isset thereon, automatic means actuated when said switch is set on restricted lines to prevent the connection of said source 1.

. naling current, an operators position, a

telephone set and supervisory signal thereat means for automatically connecting said source to non-restricted lines when the,

switch is set thereon, automatic mea-ns actuated-when said switch is set on restricted lines to prevent the connection of said source thereto and to operate sald signal, means controlled by the operator for connectingher set in circuit with the calling line, an

meanscontrolled by the operator 'for connecting said source to the line or for releasing the switch. a

3. In a telephone exchange system, the-- combination with restricted and non-rev stricted subscribers telephone lines, an automatic switch wherein said lines terminate, a side swltch therefor, senders associated with said lines adapted to set said switch thereon, a source 0 signaling current, an operators position, a telephone set and supervisory when sa1d switch is set on an idle line for signal thereat, means, actuated;

advancing said side switch to the nextposition to connect said source of signaling current to such line, a circuit closed in said position to include said source in icircu'it with the called line if such line" is a nonrestrictedline, a relay actuated when said switch is set on a restricted line for interposing' a break in said ringin circuit, a key controlled by the operator or connecting her, setto the calling line, and a key for deenergizing said relay to close the ringing circuit. 7 1

t. In a telephone exchan e system, the combination, with restricte and non-restricted telephone lines, an automatic switch wherein said lines terminate, senders associated with said lines adapted to set said switch thereon, a source, of signaling current, an operators position, atelephone set and supervisory signal thereat, means for automatically connecting said source to idle "non-restricted lines when the switch isset thereon, means actuated whensaid switch is set on restricted lines to, prevent the connection of sald source thereto and to operate suld'SlgIlul, means controlled by the operator for connecting her set incircuit with the calling line, means controlled by thev operator for connecting said source to the line, a busy back signaling apparatus at said switch, and a relay operated if the nonrestricted line is busy to prevent the opera tion of such'signal and to connect said busyback apparatus to the calling line.

5. In a telephone exchange system, the restricted and non-'recombination with stricted telephone lines, of an automatic switch wherein said linesterminate, operators equipment and a source of signaling current, means for automatically connecting said source to non-restrictedlines when the switch is set thereon, automatic means actu- I ated when said switch is set on restricted lines to prevent theconnection of said source thereto, and means controlled by the operator for connecting said source to the line.

In witness whereof, I hereunto'subscribe my name this 8th day of September A, D.,v

CHARLES L. GOQDRUM. 

